In U.S. Pat. Nos. 4,341,313 to Doring, and 4,462,500 to Konstant for example, pallet racks are disclosed in which large pallets, carrying a load of merchandise or other goods, may be stored at a front end of the rack and then rolled rearwardly to make room for placement of another pallet and load. By such apparatus, improvements in warehouse storage procedures can be obtained, in that one may eliminate aisles which extend between storage bays, since each pallet may be installed at the front end of the bay and then moved rearwardly for storage.
When access to a rearwardly positioned pallet is desired, one may simply remove the pallets in front of it with a lift truck or the like and cause the rearwardly positioned pallet to roll to the lift truck for access. Thus such systems can have a greater storage density of pallets, when compared with prior systems.
However, the systems of the prior art exhibit certain disadvantages. For example, the Doring patent requires rolling carts for holding pallets, which carts must have flanged wheels, and which must ride on wide, unprotected surfaces.
In accordance with this invention, a pallet rack system is provided with rolling carts for holding the pallets in which the wheels of the carts are not flanged, which results in a reduction in manufacturing expense, and also permits less critical control in the control of dimensions of the wheels and their placement. Additionally, in accordance with this invention, the rails upon which the wheeled carts roll may be protected to a significantly increased extent against falling debris from the pallets and the like, so that the problem of obstructions to the free rolling of the carts is significantly reduced. Additionally, the vertical space in a stack of pallet racks in accordance with this invention may be utilized in a particularly efficient manner, for improvements in storage density.
In either of the above mentioned patents, nothing prevents the second entering load from accidentally contacting and pushing the lower cart under the upper cart, causing the second pallet to be placed on the rails. This blocks placement of the third pallet. This present invention prevents this possibility.